Method of making bag closure



y 31, 1956 K. A. ARNOLD METHOD OF MAKING BAG CLOSURE Filed Nov. 14, 1950 INVENTOR. KENNETH A. ARNOLD.

MW W

ATTORNEYj.

United States Patent METHOD OF BAG CLOSURE Kenneth A. Arnold, Oswego, N. Y., assignor to St. Regis Paper Company, New York, N. Y., a corporation of New York Application November 14, 1950, Serial No. 195,555 9 Claims. (Cl. 112262) This invention relates to bag closures and to methods of manufacturing such closures and more particularly to closures for multi-walled paper bags used for holding very finely powdered material or for holding material which should be protected from moisture.

In the manufacture of heavy duty paper bags, it is customary to sever from a continuous tube or nest of tubes, bag length sections whose ends are closed by a tape folded about the ends and by stitching which passes through the tape and the ends of the sections. Usually the tape is made of paper which is pasted prior to folding about the end of a section. It is also customary to apply to one side of the tape a sealing member, usually of soft cord, and to sew through the sealing member, tape and end portions of the side walls of the bags.

The above-mentioned type of closure is satisfactory for many purposes but it will not entirely prevent the escape from the bag of finely powdered material and it is not moisture-proof, as the sealing member and the sewing thread Or stitches will absorb moisture from the atmosphere which will travel along the stitches into the closure and thus come in contact with the contents of the bag. Certain prior solutions to these problems propose to overcome these objections by dipping the bag ends in wax. These solutions are not completely satisfactory because, in each case, an added step in the manufacture of the bag is required, namely, the step of dipping the bag ends and because the dipped ends of adjacent bags tend to stick together. In addition, the ends of the bags are not as attractive in appearance, the wax rubs off in handling of the bags and when the bags are dipped after the tape has been applied, paste is normally employed to hold the tape securely against the side walls of the bag, thus requiring the use of a material which does not assist in moistureproofing the completed bag.

In accordance with my invention, I provide an improved bag closure which not only prevents the escape of very finely powdered material but also prevents the ingress of moisture through the closure. The closure of my invention is simpler and more economical than moistureproof closures of the prior art and results in a considerable saving of manufacturing time and expense.

In accordance with my invention, the tape which is applied to the ends of a bag is coated with a low melting point sealing substance, such as wax or mixtures of wax, and a resinous material, such as polyethylene, prior to the application of the tape to the ends of the bag. The low melting point sealing substance is applied to the tape in a melted state and it may be maintained in this melted state during the application and sewing of the tape to the ends of the bag so as to produce a seal between the tape and the side walls of the bag endsor the sealing substance may be melted during or after the sewing process. In the preferred embodiment of the invention, a sealing cord is applied to one side of the tape and the sewing threads pass through the sealing cord, as well as the tape, and

the bag side walls. The sewing threads and the sealing 2,756,706 P tented July 31, 1956 cord are treated with a moisture-repellent substance, such as Wax, oil, or mixtures of wax and oil.

In an alternative form of the invention, the tape is coated on one side with wax and on the other side with polyethylene prior to folding of the tape about the ends of the bags. The wax is either maintained in a melted state from the time that it is applied to the tape until after the tape is folded about the bag ends or it is melted during or after the sewing process.

The invention accordingly comprises the novel bag closure, specific embodiments of which are described herein by way of example only and in accordance with the man ner in which I now prefer to practice the invention.

The invention may be better understood by reference to the following detailed description of specific embodiments of the invention in connection with the accompanying drawing, in which:

Fig. 1 illustrates diagrammatically apparatus for making a bag closure in accordance with my invention; and

Figs. 2 and 3 are enlarged, cross-sectional and side elevation views, respectively, of the portion of the bag closure adjacent the sewing head shown in Fig. 1.

Referring to Fig. l, a tape 10, which may be either plain or creped kraft paper, is fed past a folder 11 which folds the tape about the end of a bag 12 which may be a multi-walled paper bag. The bag 12 and the tape 10 are fed together to a sewing machine of a well known type, comprising a needle 13, a presser foot 14 and a looper and feeding mechanism 15. In the preferred embodiment, a filter cord 16 is also fed to the sewing machine, and the cord 16 and the tape 10 are secured to the bag end portions or side walls by means of sewing thread 17 and looped thread 18.

Prior to being sewn to the bag, the tape 10 is coated on the side facing the bag when the bag is closed by the tape with a low melting point sealing substance. By low melting point sealing substance is meant a material which becomes soft and will flow at a temperature low enough so that the bag being closed will not be damaged at the temperature required for melting or softening the material and which retains its moisture-resistance scaling properties after the bag is sealed. The following are examples of preferred low melting point sealing substances:

(1) Wax, preferably of the microcrystalline type, having the following properties:

Melting point, ASTM F. to 170 F. Penetration, ASTM-14 to 30 Viscosity, Saybolt at 210 F.70 to Oil content4% maximum Density approximately 7 lbs. per gallon Flash point500 F. minimum Melting pointl02 C. to 108 C. Molecular weight-7000 to 12000 Other waxes and polyethylene having difi'erent properties may also be employed, but I have found that the above types give the most satisfactory results.

The low melting point sealing substance may be applied to a surface of the tape 10 in its melted state and then allowed to cool forming a solid layer of the substance on the tape. The tape may be applied to the ends of the bags while the substance is in this solid state and during or after its application thereto, heat may be applied to cause the substance to soften or melt and to flow into the needle holes and between the tape and the side walls of the bag, thus forming a dust and moistureproof seal at the end of each bag. However, in the preferred form of the invention, as shown in Fig. l, the sealing substance in a melted state is applied continuously to the tape as it is folded about the ends of the bags and fed to the sewing machine.

In Fig. 1, the paper tape 10 is fed from a roll 19, under a guide roller 20, over a roller 21 immersed in melted sealing substance 22, under a guide roller 23 and past a twisting roller 24. The sealing substance 22 is contained in a melting pot 25 which is heated by any well known means, such as an electric heating coil 26. When the above-mentioned mixture of wax and polyethylene is employed as a sealing substance, the mixture preferably should be kept at a temperature of 100 C., and if wax alone is employed, the wax may be kept at a temperature in the range from 85 C. to 100 C.

When the sealing substance is applied to the tape 10, as indicated in Fig. 1, it is normally still in a melted or softened state, as the tape is folded about and sewn to the end of a bag, but to make certain that it is still melted during the sewing process, the substance may be heated at the sewing machine, as by a heat lamp 27. If desired, the substance may also be heated after the tape is sewn to the bag, as by a heat lamp 28, but usually such after-heating is unnecessary.

To further aid in creating a moisture and dustproof seal at the ends of the bags while retaining the advantages of the seal described above, the tape 10 may be coated on its surface opposite to the one on which the aforementioned sealing substance is applied with polyethylene. The tape may be prepared, for example, by coating one surface of commercially available creped kraft paper having a stretch in the range from to and weighing 60 lbs. per ream with to lbs. per ream of polyethylene having a molecular weight of 19,000. This tape is then applied to the bag ends in the manner described above with the side coated with polyethylene, as just described, facing away from the bag.

In addition to providing a layer of a low melting point sealing substance under the tape 10, the sewing thread 17, and optionally the looper thread 18, should preferably be treated with a moisture-repellent substance so as to assist in preventing moisture from entering the bags by way of the thread. The thread is preferably impregnated with wax of the type described above or with one of the following substances:

(1) No. l paratfin oil, such as that supplied by the Sinclair Refining Co. or the Socony-Vacuum Oil Co.

(2) A mixture of between 20% and 50% by weight of crude scale wax having a melting point of 120 F. dissolved in the No. l paraffin oil mentioned above.

When wax alone is used to impregnate the thread, the thread may be immersed in the melted wax until it is saturated and then it is removed, drained and cooled. The thread is then ready to use and may be fed directly to the needle 13 but alternatively and preferably, untreated thread may, as shown in Fig. 1, be fed from a cone 2& to the needle 13 through a pot containing the melted wax and heated as by the electric heating element 31. With this latter method, the thread is substantially continuously fed over a pair of guide rollers 32 and 33 under an immersion roller 34 and between a pair of squeezing rollers 35 and 36. The rollers 35 and 36 squeeze or press out the excess wax which drains back into the pot 30.

When the above-mentioned parafiin oil is employed to impregnate the thread, the thread may be immersed in the oil for 24 hours and then drained for about 48 hours, both steps taking place at temperatures between 60 F. and

100 F. The thread may then be fed directly to the needle 13, but alternatively and preferably, the pot 30 may contain oil instead of wax, and untreated thread 17 may be fed through the pct 30 in the manner described above in connection with the second method for impregnation of the threaded by melted wax.

When the above-mentioned mixture of paraffin oil and wax is employed to impregnate the thread, the thread may be immersed in the mixture at a temperature between F. and F. until saturated and then removed and drained or squeezed to remove any excess of the mixture. In this case, also, the thread is ready for sewing without any further treatment, but preferably again untreated thread may be fed from the cone 29 to the pot 30 and thence to the needle 13 by way of the rollers 3236, the pot 30 in this case being filled with the mixture of paraifin oil and wax maintained at a temperature between 140 F. and 160 F.

In the preferred form of the invention, a filter cord extending along the side of the tape 10 is also employed for its well known advantages. This filter cord, indicated by the numeral 16 in Fig. l, is preferably also treated with a moisture-repellent substance of the type used to treat the sewing thread 17. The filter cord 16 may be impregnated with wax, oil, or wax and oil, or with molten polyethylene, by immersion and the fed directly to the needle 13 in the manner first described in connection with each of the methods for treating the sewing thread 17. Howeven untreated filter cord preferably is fed from a cone 37 over a pair of-guide rollers 38 and 39, under an immersion roller 40 and between a pair of squeezing rollers 41 and 42. The immersion roller 40 immerses the cord in the moisture-repellent substance, such as wax, oil, or a mixture of wax and oil, or molten polyethylene, contained in the pot 43 which may be heated as by an electric heating element 44.

It will be noted that when the thread 17 and the cord 16 are treated with a low melting point substance, such .as wax, the substance will be heated and melted or softened by the lamp 27 and/or 28 during or after the sewing process, hence, the needle holes will be filled and the thread 17 and cord 16 will be sealed against moisture. However, the treatment of the thread 17 and cord 16 is such that there is no excess of the moisturerepellent substance so that the closure remains neat in appearance and there is little or no substance exposed thereby to cause stickiness.

Figs. 2 and 3 show in cross section and side elevation, respectively, a portion of a partially completed bag closure. In these figures, a multi-walled paper bag 45 whose side wall is folded inwardly at the portion 46 is enclosed at its end by the tape 10. Between the tape 10 and the side walls of the bag 45 is a layer 47 of a low melting point sealing substance. The tape 10 is secured to the side walls of the bag 45 by means of sewing thread 17 and looper thread It as well as by the layer of sealing substance 47. The filter cord 16 extends along one side of the tape 10 and is secured to the side of the tape by the sewing thread 17. It will be seen that the tape 10 extends a short distance beyond the end of the bag 45 and the folded portions are sealed and sewn together.

It will be obvious that although I have not shown a complete bag in Figs. 2 and 3, the remaining portion of the closure will have the same construction as that shown in Figs. 2 and 3. In addition, it will be obvious that the apparatus shown may be employed to manufacture bag closures for bags fed one after the other to the sewing machine rather than fed individually to the sewing machine, as shown in Fig. 1.

Having thus described my invention with particular reference to the preferred form thereof and having shown and described certain modifications, it will be obvious to those skilled in the art to which the invention pertains, after understanding my invention, that various changes and other modifications may be made therein without departing from the spirit and scope of my invention, as defined by the claims appended hereto.

What is claimed as new and desired to be secured by Letters Patent of the United States is:

1. The method of closing the end of a bag which comprises coating a tape with wax, folding said tape about the adjacent ends of said bag with the wax between said tape and said ends, applying a wax treated sealing cord to said tape at one side thereof, sewing said cord and said tape to the side walls of said bag with wax treated thread and causing said wax on said tape, said thread and said cord to assume a melted state when the tape encloses said ends.

2. The method of closing the end of a bag which comprises coating a tape with wax, folding said tape about the adjacent ends of said bag with the wax between tape and said ends, applying a wax treated sealing cord to said tape at one side thereof, sewing said cord and said tape to the side walls of said bag with oil treated thread and causing said wax on said tape and said cord to assume a melted state when the waxed surface of the tape is in contact with said ends.

3. The method of closing the end of a bag which comprises the steps of coating a tape with a low melting point sealing substance, folding said tape about the adjacent ends of said bag impregnated with a low melting point sealing substance, applying a sealing cord with the sealing substance between said tape and said ends to said tape at one side thereof and sewing said cord and said tape to the side walls of said bag with thread impregnated with a moisture repellent substance and the step of melting said sealing substance during one of said folding and sewing steps.

4. The method of closing the end of a bag which comprises the steps of coating a tape with wax, folding said tape about the adjacent ends of said bag with the wax between said tape and said ends, applying a wax treated sealing cord to said tape at one side thereof and sewing said cord and said tape to the side walls of said bag with wax treated thread and the step of melting said wax on said tape during one of said folding and sewing steps.

5. The method of closing the end of a bag which comprises coating a tape with melted wax, folding said tape about the adjacent ends of said bag with the wax between said tape and said ends, applying a wax treated sealing cord to said tape at one side thereof, sewing said cord and said tape to the side walls of said bag with wax treated thread and maintaining said wax in a melted state during the folding and sewing of said tape.

6. The method of closing the end of a bag which comprises coating a tape with melted wax, folding said tape about the adjacent ends of said bag with the wax between said tape and said ends, applying a wax treated sealing cord to said tape at one side thereof, sewing said cord and said tape to the side walls of said bag with oil treated thread and maintaining said wax on said tape and said cord in a melted state during the folding and sewing of said tape.

7. The method of closing the end of a bag which comprises the steps of coating a tape with a low melting point sealing substance, folding said tape about the adjacent ends of said bag with said substance between said tape and said ends, and sewing said tape to the side walls of said bag with thread impregnated with a low melting point sealing substance, and the step of melting said sealing substance during one of said folding and sewing steps.

8. The method of closing the end of a bag which comprises the steps of coating a tape with a low melting point sealing substance, folding said tape about the adjacent ends of said bag with said substance between said tape and said ends, and sewing said tape to the side walls of said bag with thread impregnated with wax, and the step of melting said sealing substance and said wax during one of said folding and sewing steps.

9. The method of closing the end of a bag member with a tape member folded about the end thereof which comprises the steps of coating one of said members with a low melting point sealing substance, folding said tape member about the adjacent ends of said bag member with said substance between said tape and said ends, and sewing said tape member to the side walls of said bag member with thread impregnated with a low melting point sealing substance, and the step of melting said sealing substance during one of said folding and sewing steps.

References Cited in the file of this patent UNITED STATES PATENTS 1,449,467 Walter Mar. 27, 1923 1,734,287 Cornell Nov. 5, 1929 1,916,854 Bischofl July 4, 1933 2,189,067 Hlavaly Feb. 6, 1940 2,242,857 Fortuin May 20, 1941 2,314,819 Ewer Mar. 23, 1943 2,373,010 Brady Apr. 3, 1045 2,403,756 Read July 9, 1946 2,406,791 Belcher Sept. 3, 1946 2,409,621 Geimer et al. Oct. 22, 1946 2,418,169 Fredericksen Apr. 1, 1947 

